[plt-scheme] bootstrapping scheme

Hi all,

sorry for the only vaguely related topic, but does somebody here know 
about an implementation of a more normal scheme on top of a very minimal 
scheme?
The system I'm looking for should provide all these elements by 
expanding input strings into code formats which are compliant with the 
lower-level system (typical bootstrapping).


I am trying to get a scheme running in a system that I'm building but 
currently I only have lambda, set!, numbers, strings, symbols, chars 
etc; but no parser whatsoever nor support for syntaxes etc. I would like 
to be able to program a little bit my scheme-like in my program; but I'd 
hate to reinvent the wheel by having to write the bootstrapping myself. 
Obviously I can meet somewhere in the middle if somebody has interesting 
pointers.

cheers,
Toon Verwaest